Qt DoubleSpin Box value changed slot has called twice
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I have created a sample application, it contains only QtdoubleSpinbox.
I have not overridden any methods.below is my CPP code
#include "mainwindow.h" #include "ui_mainwindow.h" #include "qdebug.h" #include <qspinbox.h> MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) { ui->setupUi(this); connect(ui->doubleSpinBox, SIGNAL(valueChanged(QString)), this, SLOT(on_doubleSpinBox_valueChanged1(QString))); } MainWindow::~MainWindow() { delete ui; } void MainWindow::on_doubleSpinBox_valueChanged1(const QString &arg1) { qDebug()<<"doubleSpinBox value changed: "<<arg1; }@Sowmiya-R
Must be something in your Qt/compiler I guess ??
Can you try this test
https://www.dropbox.com/s/9eftxqghndn2bhw/myspinbox.zip?dl=0 -
wrote on 9 Aug 2017, 11:12 last edited by
@Sowmiya-R ,
Hi,
You can use Qt::UniqueConnection in Connect statement. -
@Sowmiya-R
Must be something in your Qt/compiler I guess ??
Can you try this test
https://www.dropbox.com/s/9eftxqghndn2bhw/myspinbox.zip?dl=0 -
I have tested your code.
I am able to reproduce the same in debug mode.
Can you please put a break point in slot function and run it in debug mode and see.@Sowmiya-R
Ahh, now i see.
Yes the debugger seems to interfere with event loop so it does indeed call it twice on one click
if u place break point there. Else Not.void MainWindow::on_doubleSpinBox_valueChanged(const QString &arg1) { static int hmm=0; qDebug() << arg1; hmm++; qDebug() << hmm; }"1,00"
1
"2,00"
2I would guess that pausing it triggers the repeat feature and since it dont get an mouse release event its why.
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wrote on 10 Aug 2017, 05:25 last edited by
I have developed a application using Qt, there regardless of debug mode or release mode value changed slot has called twice only on spinbox box up/down controls.
I try to reproduce the same in sample application, but its happening only in debug mode.There is something missing in my application. I will check it out.
Thank you guys for you suggestions. -
I have developed a application using Qt, there regardless of debug mode or release mode value changed slot has called twice only on spinbox box up/down controls.
I try to reproduce the same in sample application, but its happening only in debug mode.There is something missing in my application. I will check it out.
Thank you guys for you suggestions.But it ONLY happens for me if i set break point.
Never, ever else.Do it happen for you if yo have NO break points ?
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But it ONLY happens for me if i set break point.
Never, ever else.Do it happen for you if yo have NO break points ?
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@Sowmiya-R
Ok, that does not happen for me.
Without break point it works correctly here.I have no idea what could be wrong with your Qt.
Since you are using a clean project to test, i assume is something with your pc or Qt.
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The double call to slot happened in my case only with a breakpoint in the slot function, otherwise it is called once only. The second call was triggered by a timer event
wrote on 22 Dec 2020, 10:41 last edited by JonB@Wael11
For anyone reading this: This is known behaviour, which I stumbled across a long time ago and it was infuriating.With a
QSpinboxQt Internal code uses a timer on clicks/presses. If you step through in debugger you exceed the timeout and get bad/double behaviour.Simplest: change all
connect()toQSpinboxclick/key to passQt::QueuedConnectionas last parameter for connection type, not defaultQt::DirectConnection. Now you can use debugger breakpoints and all will be well. I wrote a method to connect all my spinboxes like this.
